| Non-thermal plasma surface modifications have become indispensable processing steps in various industry and research sectors. Applications range from semiconductor processing to biotechnology and recently, plasma medicine. Non-thermal plasma sources have the advantage that a number of electron-driven chemical reactions can be produced while maintaining the gas (heavy species) temperature low, thus enabling the treatment of temperature-sensitive surfaces such as polymers, tissues and live cells. In the fields of biology and medicine, non-thermal plasmas have been primarily used for the deposition or modification of biocompatible polymers and for sterilization. Recently, non-thermal plasmas have been used to treat tissues and cells. A new field of research has emerged, Plasma Medicine, which studies the effects of non-thermal plasmas on cells and tissues for clinical applications.;However, while investigating the mechanisms involved in cell transfection we observed that the use of higher gas flows in the negative controls (using the APGD-t but with the plasma turned off) also resulted in cell transfection. To further study this phenomena, we built a simple transfection device consisting of a straight glass capillary tube and a plastic support. Using three different gases and five different capillary diameters, we were able to relate the transfection efficiency to the dynamic pressure of the gas exiting the capillary tube.;Finally, even though transfection of cells seem to depend more on the mechanical forces exerted by the gas flow than on the effects of the plasma, other applications of non-thermal plasma in the field of medicine are in development. However, published studies have focused on only the positive effects of non-thermal plasmas, neglecting the potentially induced adverse effects. Therefore, we studied if damage could be caused in cells following an indirect (APGD-t) or a direct (parallel electrodes DBD) plasma treatment. We found that a low power direct plasma treatment caused oxidative stress in HeLa cells. Both plasma sources were shown to produce DNA double-strand breaks but no lipid peroxidation. Also, the sequencing of plasma-treated naked plasmid DNA introduced in electrocompetent bacteria showed no evidence of mutations.;The Atmospheric Pressure Glow Discharge torch (APGD-t), a non-thermal plasma source, built in our laboratory was used to study the effects of non-thermal plasmas on mammalian cells. In its first application, we indirectly used the APGD-t to deposit a plasma-polymer on a glass surface and studied its effects on cultured cells. It was shown that the cells grew preferentially on the plasma-polymer, and their proliferation rate increased. The second application of the APGD-t was to further investigate previous observations of cell permeabilization obtained by plasma treatments and to apply non-thermal plasmas to cell transfection. It was demonstrated that the APGD-t is able to locally transfect adherent cells. We estimated the diameter of the pores created to be below 10 nm and that the pores remain open for less than 5 seconds. |
